Musical instruments at yard sales?

Last weekend, Frank invited me to go to the big yard sale/flea market being held at the armory. Having nothing else to do, and being a rainy day, I agreed. I was quite surprised to see one person’s booth was full of used musical instruments and accessories, (for example, a few Marshall and fender amplifiers and a variety of different microphones, and guitar pedals.) I don’t know if I would trust buying anything like that at a yard sale or flea market. Even if they had the ability to plug them in and test them to prove that they work, I’d be really reluctant. I think I’d be more inclined to purchase them through a store – or at least from a trusted friend!